The dealer-locator service connects a caller to the one of a plurality of business locations of the called party (the "dealer") which is closest to the caller. The dealer-locator service is well-known for stationary calling stations (i.e., conventional wired-in-place telephones). The service uses the calling telephone number to determine the caller's geographical location, and from that information determines the called party's business location that is geographically closest to the caller. Illustrative implementations of the dealer-locator service are disclosed in U.S. Pat. Nos. 4,757,267 and 5,136,636.
While the known dealer-locator service works well for stationary communications stations, it is practically useless for mobile (i.e., portable) communications stations, such as mobile cellular radiotelephones and personal communications services (PCS) wireless handsets. The reason is that the known service uses the calling station's telephone number to derive the caller's geographical location. But the geographical location of a mobile station changes while its telephone number remains the same. Hence, the telephone number of a mobile station is not representative of its location.
Schemes for determining the geographical location of a mobile station are known. One scheme, disclosed in U.S. Pat. No. 5,293,645, uses relative transmission-propagation delays from a mobile station to a plurality of base stations to determine the mobile station's location by using triangulations or other geographical intersection techniques. Consequently, this scheme works only when the mobile station is in simultaneous communication with a plurality (generally at least three) of base stations. Another scheme, disclosed in U.S. Pat. No. 5,479,482, equips each mobile station with a global satellite positioning (GPS) device that determines and reports the mobile station's geo-coordinates, which can then be converted into location information. Consequently, this scheme works only for specially-equipped mobile stations, but not for conventional mobile stations without a GPS device. Neither scheme is therefore useful for implementing a ubiquitous dealer-locator service for conventional mobile telecommunications systems.